BluePill delayMicroseconds issue

Hi all

have LCD project ongoing but is time crucial and I need clear 1us delay but on sample I have on LED if I put delayMicroseconds(1) in reality is bit different
Here is LogicAnalyzer image

How can this be done to get normal 1us delay ???

P.S.
delay in ms works fine

one approach: http://www.stm32duino.com/viewtopic.php?t=326

-rick

Or turn off interrupts and use “nop”s

Here is update with @Rick implementation

small difference shouldn’t effect a lot (on 100us got 100.1us)
but it is working nice

Thx a lot for help

Are you sure the timing on your logic analyser is accurate to a few hundred nano seconds ?

RogerClark wrote:Are you sure the timing on your logic analyser is accurate to a few hundred nano seconds ?

I have a 100Mhz analyser and also a 100Mhz bandwidth scope, if you OP could post the exact code I could look at it on those.

I have tested on @Rick blink sample and measure on Rigol 100Mhz
here is output and it looks OK

trying to replicate issue for STM library SPL and HAL but can’t get correct value
Does anybody knows what is so special/different in Arduino code that works normally but on SW4STM32 and ST libs I can’t get same timings

Here is my example I’m trying to replicate and for ms is working fine (got 1.01ms)
but if I run _delay_us(1) I get strange value (2.25us) and that is lowest value I can get
P.S. (with GPIO_SetBits/GPIO_ResetBits that same value is 2.625us)

Do I need to configure clocks/interupts or what to get same timing like STMduino???
Where did I make mistake? Anyone faced similar issue?

#include "stm32f10x.h"

void _delay_us(uint32_t us);
void _delay_ms(uint32_t ms);
void InitGPIO();

int main(void) {
InitGPIO();
while (1) {
GPIOC->ODR = 1<<13;
_delay_ms(1);
GPIOC->ODR = 0<<13;
_delay_ms(1);
}
}

void InitGPIO() {
//def port C (LED)
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
GPIO_InitTypeDef GPIO_InitStructureC;
GPIO_InitStructureC.GPIO_Pin = GPIO_Pin_13;
GPIO_InitStructureC.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructureC.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructureC);
}

void _delay_us(uint32_t nus) {
u32 temp;
SysTick->LOAD = 8 * nus;
SysTick->VAL = 0X00;
SysTick->CTRL = 0X01;
do {
temp = SysTick->CTRL;
} while ((temp & 0x01) && (!(temp & (1 << 16))));
SysTick->CTRL = 0x00;
SysTick->VAL = 0X00;
}

void _delay_ms(uint32_t nms) {
u32 temp;
SysTick->LOAD = 9000 * nms;
SysTick->VAL = 0X00;
SysTick->CTRL = 0X01;
do {
temp = SysTick->CTRL;
} while ((temp & 0x01) && (!(temp & (1 << 16))));
SysTick->CTRL = 0x00;
SysTick->VAL = 0X00;
}


Libmaple sets up systick to increment every millisecond.